Polymer composed of sulfonium salts



Unitcd States Patent 3,216,979 POLYIVLER COMPOSED 0F SULFONIUM SALTS David R. Sexsmith, Stamford, Conn., and Everett Frazza, Yorktown Heights, N.Y., assignors to Amencan Cyanamid Company, New York, N.Y., a corporation of Maine No Drawing. Filed Mar. 9, 1961, Ser. No. 94,423 3 Claims. (Cl. 26079.3)

This invention relates to water-soluble copolymers containing ternary sulfonium salt groups. More particularly, this invention is directed to novel aqueoussoluble copolymeric compositions obtained by reacting a copolymer of ar-substituted haloalkyl styrenes and a styrene or a different substituted styrene monomer with certain di-substituted sulfides.

The linear chain copolymers of the invention are thermoplastic resinous polymerization products consisting essentially of two clases of monomers. The first class, which is preferably employed in minor amounts, i.e.,

'less than 25% by weight, is a monoethylenically unsaturated monomer containing a CH =C or vinyl group having attached thereto aromatic substituents consisting more specifically of an aromatic ring containing thereon, as an essential part, a halogenated alkyl radical. The monomers of the second class, namely the styrene or substituted styrene monomers, are also monoethylenically funsaturated compounds capable of copolymerizing with those ofthe first type through a CH =C group but are distinguished from the first type as not containing a halogenated alkyl radical. The invention is particularly concerned with the advantages afforded by subsequent treatment with organic sulfides of the copolymerization product of these two specific types of monomers, but it will be understood that other copolymerizable compounds may also be present in minor amounts of up to about 15 of the weight of the copolymer in some cases.

Typical among this first type of monomers are polymerizable compounds represented by the formula wherein R and R are substituents selected from the group consisting of hydrogen, halogen, methyl and ethyl radicals, R is a substituent selected from the group consisting of methylene and ethylene radicals, and X is a halogen atom. Examples of this type of compound are those such as ar-(chloromethyl)styrene, ar-(l-chloroethyl)styrene, ar-(bromomethyl)styrene, ar-(l-bromoethyDstyrene, p-chloro ar (chloromethyl)styrene, armethyl-ar-bromomethylstyrene, ar-ethyl-ar-chloromethylstyrene, ar-methyl-ar-chloromethyl-styrene, p-chloro-arl-chloroethyl) styrene, tat-methyl ar-( 1-chloroethy1)styrene, p bromo-ar(chloromethyl) styrene, a methyl ar- (chloromethyl)styrene, and the like.

Examples of the styrene or substituted styrene monomers which are employed in the preparation of copolymers with which the invention is specifically concerned are compounds of the general formula 3,216,979 Patented Nov. 9, 1965 "ice wherein R is a substituent selected from the group consisting of hydrogen and methyl radicals and R is a substituent selected from the group consisting of hydrogen, methyl, ethyl, propyl and halogen radicals. Suitable compounds of this type are those such as styrene, methyl styrene, ethyl styrene, propyl styrene, chlorostyrene,

bromostyrene, fluorostyrene, iodostyrene, a-rnethyl styrene, a-methyl methylstyrene, a-methyl ethylstyrene, amethyl propylstyrene, oc-methyl chlorostyrene, a-methyl bromostyrene, a-methyl fluorostyrene, a-methyl iodostyrene and the like. 7

The relative mole ratios of the copolymerizable components may vary from about 1 to about 25 mole percent of the ar-substituted haloalkyl styrenes and from about to about 99 mole percent of the styrene or substituted styrene monomers and preferably a mole ratio of ar-substituted haloalkyl styrene to styrene or substituted styrene monomer in the range of about 1:99 to about 10:90, respectively.

It is understood that within the scope of the invention mixtures or blends of the monomers of the first type may be copolymerized with mixtures or blends of monomers of the second type.

It may be desirable to modify these copolymers by the addition of up to about 15% of a third and different polymerizable monomer during the copolymerization re action. Suitable compounds are the polymerizable monomers containing a CH =C group. Exemplary of such monomers are vinyl chloride and vinylidene chloride; the vinyl esters, such as vinyl acetate, ethyl acrylate, ethyl methacrylate, methyl methacrylate, etc. and conjugated diolefins, such as butadiene, isoprene, chloroprene, 2,3- dimethyl butadiene, and the like.

The copolymer is insoluble in water and the formation of the sulfonium salt effects Water-solubility. The reaction of the copolymer with the organic sulfide converts the non-ionic nature of the copolymer to a novel product which is cationic and substantive to cellulose. When the resin is so conditioned it is selectively adsorbed or absorbed by the cellulose fibers from a dilute aqueous solution or dispersion thereof, containing these fibers, in amounts much greater than those corresponding to the concentration of resin in the solution or to what would be contained in the water normally left in the sheet after forming.

The copolymerization of the vinyl aromatic compound containing the alkyl halogen radical and the styrene or substituted styrene compound can be effected by any of the procedures known to be suitable for polymerizing vinyl compounds. Thus thermal or ultraviolet light polymerization may be employed. Preferably a small quantity, on the order of 0.1% to 2% on the weight of the monomers, of a suitable polymerization initiator, such as azobisisobutyronitrile, benzoyl peroxide, cumene hydroperoxide, pinane hydroperoxide, and the like, is added, after which the reaction mixture is heated at temperatures of about 50 C. to C. until the copolymerization has been carried to the desired extent. Bulk polymerization procedures may be used in which the reagents are simply heated together in a closed vessel, or the polymerization can be carried out in an organic solvent, such as dioxane, toluene, or other aromatic hydrocarbon solventknown in the art to be suitable for this purpose.

The presence of Water-soluble material in the aqueous solution of the salts of the copolymers is not excluded. For example, cooked starch may be employed to further enhance the properties which are imparted by the resin without losing any advantages afforded by the copolymers of this invention.

7 Suitable di-substituted organic sulfides which may be utilized in preparing the ternary sulfonium salt of the arhaloalkyl radical on the ring of vinyl aromatic units in the copolymer are those of the formula wherein R and R' are substituents selected from the group consisting of alkyl radicals of l-6 carbon atoms, aryl, aralkyl and alkaryl radicals. Illustrative compounds are such as dimethyl sulfide, methyl ethyl sulfide, diethyl sulfide, dipropyl sulfide, dibenzyl sulfide, di-tertiary butyl sulfide, methyl butyl sulfide, ditolyl sulfide, ditoluyl sulfide, ethyl hexyl sulfide, ethyl toluene sulfide, and the like.

In preparing the sulfonium salt, the sulfide, preferably in excess of an equal molar ratio, based on the amount of ar-haloalkyl substituted styrene, is employed although amounts even less than equal molar quantity of the sulfide compound may be sufiicient. In general, quantities of the sulfide compound to ar-haloalkyl substituted styrene in the copolymer in a molar ratio of from about 0.8:1 to about 2.0:1, respectively, may be used. Larger relative quantities of the sulfide may be used but no particular advantage accrues thereby.

The temperature employed in the reaction of the copolymer and the sulfide may vary from about room temperature to reflux. It is preferred that temperatures in the range of from about 40 C. to about 80 C. be employed.

The sulfonium salt prepared from the copolymer according to the invention may be represented by the general formula wherein R through R and X have the values hereinabove defined and the mole ratio of a to b is from about 99:1 to about 72:25, respectively.

From a practical standpoint, the copolymer is dissolved in a water-miscible organic solvent and reacted with the ternary sulfide. As the reaction proceeds, the hydrophobic copolymer becomes more water-soluble and water may be added to the solution to maintain solubility. In some cases, depending upon the choice of solvent and copolymer, solubility will be maintained without the addition of Water. Water-miscible organic solvents for this purpose are such as dioxane, dimethyl formamide, nitromethane, butyl cellusolve, ethyl cellusolve, or various water-miscible alcohols i.e., diglyme and ketones, i.e., methyl ethyl ketone.

The molecular weights of the copolymers are not critically important, inasmuch as water-soluble products are obtainable over a wide range of molecular weights. The more useful properties are obtained when the copolymers have attained molecular weights of at least 10,000 although it will be understood that the resins produced by the above-described processes ordinarily have molecular Weights susbtantially higher than this minimum and usually within the range of about 50,000 to 800,000 and even higher. The molecular weights of the polymers were determined by measurement of the intrinsic viscosity of the polymer backbone, i.e. before reaction thereof with the sulfide, in benzene at 30 C.

It will be seen, therefore, that the linear carbon chain polymers used in preparing the cationic sulfonium salts of the invention are the copolymerizates of (a) polymerizable ar-substituted vinyl aromatic, which substituents are halogenated alkyl radicals of 1 to 2 carbon atoms, and (b) styrene or substituted styrene monomers copolymerizable with (a). All or part of the halogens in the vinyl aromatic alkyl group in the straight chain copolymer are converted to salt groups by reacting the copolymers with (c) the sulfides of the general formula hereinbefore described.

Because of their water solubility, these resinous ternary sulfonium salts can be economically applied to surfaces. They have been found to confer unusually good soil conditioning properties to soil, unusual sizing properties to paper substrates to which they have been applied, and are excellent corrosion inhibitors for metals when used in metal treating baths.

In order that the present invention may be more fully understood, the following examples are set forth for purposes of illustration only, and any specific enumeration of details should not be interpreted as a limitation, except as expressed in the appended claims. Parts expressed are parts by weight, unless otherwise stated.

Example 1 25 parts of styrene and 304 parts of chloromethyl styrene were dissolved in 25 parts of benzene. To the solution was added 0.28 part of benzoyl peroxide. The solution was refluxed for 6 hours and then the reaction mixture was poured into 250 parts of methanol. A white gum resulted which was dissolved in methyl ethyl ketone and reprecipitated with methanol resulting in the production of 15 parts of a white polymeric solid.

Example 3 The following were placed in a suitable reaction vessel.

Parts Styrene 43.5 Chloromethyl styrene 5.0 Ethyl acrylate 1.5

Benzoyl peroxide 0.25

The vessel was sealed and heated to C. for 48 hours. The product was worked up as in Example 1. 48.5 parts of the solid polymeric material were recovered.

Example 4 90 parts of styrene and 10 parts of chloromethyl styrene were copolymerized following the procedure of Example 1. The polymer was dissolved in parts of diglyme and treated with 4.0 parts of diethyl sulfide. The resultant mixture is fiushed with nitrogen and heated at 65 C. for 5 hours to produce the water-soluble salt of the copolymer. The product is composed of recurring units of the formula in a ratio of a to b of about 9:1.

Example 5 45 parts of styrene and 8 parts of bromomethyl styrene WW? c p lymerized utilizing the procedure of Example l. The copolymeric product is then reacted with methyl ethyl sulfide (3.5 parts). The resultant salt product is Water-soluble.

Example 6 85 parts of methyl styrene and 15 parts of chloroethyl styrene were copolymerized according to the procedure of Example 1. The resulting copolymer was then reacted with 12 parts of dimethyl sulfide, yielding a watersoluble product.

Example 7 A copolymer of propyl styrene (90 parts) and fluoroethyl styrene (10 parts) were prepared following the procedure of Example 1. The polymer was dissolved in 50 parts of methyl ethyl ketone. To this solution was added 6 parts of dibenzoyl sulfide. The resulting solution was refluxed for 7 hours. The solution was then diluted with water. The resulting solution had a concentration of only 3.89% solids.

In each of Examples 4 to 7 hereinabove, a positive halogen ion test is obtained with silver nitrate.

The products obtained for Examples 4 to 7 are very effective metal corrosion inhibitors in amounts of from about 0.1 to about 3% based on the weight of solution when used in metal treating baths. The sulfonium copolymeric salt apparently forms a monomolecular layer on the metal. The products herein prepared are also useful in the selective sepaartion of ores in ore settling operations.

We claim:

1. A water-soluble copolymeric composition consisting essentially of recurring units of the formula tan 1 and methyl radicals; R is a substituent selected from the group consisting if hydrogen, methyl, ethyl, propyl and halogen radicals; R and R are substituents selected from the group consisting of alkyl radicals of 1-6 carbon atoms, aryl radicals, alkaryl radicals and aralkyl radicals; and X is a halogen atom, and the mole ratio of a to b is from bout 99:1 to about :25, respectively.

2. A water-soluble copolymeric composition consisting essentially of recurring units of the formula wherein R and R are substituents selected from the group consisting of alkyl radicals of 1-6 carbon atoms, aryl radicals, alkaryl radicals and aralkyl radicals, and the mole ratio of a to b is from about 99:1 to about 75:25, respectively.

3. A water-soluble copolymeric composition consisting essentially of recurring units of the formula Clb wherein the mole ratio of a to b is from about 99:1 to about 75:25, respectively.

References Cited by the Examiner UNITED STATES PATENTS 2,8 00,747 7/57 Pitt 47-5 8 2,895,925 7/ 59 Hwa 2602.1 3,078,259 2/ 63 Hatch 26079.7 3,13 0,117 4/64 Humiston 26079.7

JOSEPH L. SCHOFER, Primary Examiner.

HAROLD N. BURSTEIN, WILLIAM H. SHORT,

Examiners. 

1. A WATER-SOLUBLE COPOLYMERIC COMPOSITION CONSISTING ESSENTIALLY OF RECURRING UNITS OF THE FORMULA 